Many components for aircraft nacelles are manufactured using composite materials. Composite materials tend to have a high strength-to-weight advantage compared to traditional metals. One particular application for the use of composite materials is for fabricating panels. One type of panel may include a single skin with multiple laminar layers that are formed from composite materials such as graphite or an aromatic polyamide fiber of high tensile strength that are embedded in a resin matrix. One or more stiffening members, sometimes referred to as “hollow hats” due to their cross-sectional shape, may extend from the inside (non-aerodynamic) surface of the skin to provide additional strength to the panel. In some cases, a mandrel is used to form the shape of the stiffening member, and the composite skin is co-cured with the stiffening member with the mandrel in place. After the curing process, the mandrel is removed from the panel. However, after the curing process, there may be a significant amount of friction between the mandrel and the panel, and it may be difficult to remove the mandrels in a consistent manner which minimizes the possibility of damage to the cured panel or to the mandrel.